Accuracy of Pedicle Screw Placement in Thoracic Spine Fractures

Transpedicular instrumentation in the thoracic spine is technically difficult because of small pedicle diameters. There are not many studies assessing in vivo accuracy, complications, and the revision rate of transpedicular screws in the thoracic spine. In this retrospective study 278 thoracic pedicle screws of 43 patients were assessed using a scoring system and postoperative computed tomography (CT) scans. 43 consecutive patients with traumatic thoracic spine fractures underwent posterior transpedicular reduction and fixation. The universal spine system was used for placement of 278 pedicle screws under fluoroscopic control. Fractures were classified according to the Magerl classification by plain radiographs and CT scans. Evaluation of pedicle screw placement was assessed by a scoring system from grade I to grade III. Revision rate of pedicle screws as well as pre- and postoperative neurologic status were analyzed. In the thoracic spine, vertebral body T7 was mainly fractured followed by T6 and T5. In 37 (86.0%) of 43 patients type C fractures and in three patients each type A and B fractures were determined, respectively. Of all 278 pedicle screws, 78.1% were inserted in pedicles T4–T9. The rate of optimally placed grade I screws was 84.5%. Grade II screws were scored in 6.8% and grade III screws in 8.6%. The revision rate of all pedicle screws was 5.0%, whereas 64.3% of these were grade III. None of the patients suffered neurologic or vascular structure compromise postoperatively. Although most pedicle screws were placed in pedicles of the middle thoracic spine where the pedicle width is smallest, most screws were optimally placed with grade I. The revision rate of pedicle screws was acceptable and associated with the grade of pedicle screw placement.